I would like to create a shared directory where users will have access to all files in read and write mode, even if the file has been created by another user.To do this, I think the ACLs is the good thing, but the command setfacl does not work, with a Operation not supported error.

Is ACL option set in this kernel ? Is it in the newer kernel ? What is the best way to do what I want ?

No, acls are not working with 777 rights, and with the 777 it won't work. Imagine user user1 create file testThis file will be owned by user1user2 won't have rigths to modify file test ;-)

They will if the file has a 777 mode. But this isn't related to the mode on the directory - it's related to the umask set for the process creating the file.So, if you have control over the application used to modify the files you could try setting a umask of 0 for the processes concerned (an interlude shell script, for instance).

It won't work ! I may create a file through ssh in vim, or copy a video file, anything, any time !The proper solution I found is acls. I mounter the partition with acls enabled, and no errors appeared, but setting the acls to the directory I want to be public is not working (setfactl)This might be due to no ACL support in the base kernel. But I don't know how to check this...

Since you're using the original kernel, my guess is that you're using the original NAND-based jffs2 file system. I honestly don't know, but it would not surprise me to learn that jffs2 doesn't support ACLs. (Does anyone know?) This may be why you are seeing the setfacl errors.

That said, I think that, rather than ACLs, what you need is a way to make all files created in the shared directory mode 0666. I don't know of any directory specification that will do this trick, but you could use wrapper scripts or a cron job to do this. The real problem is making sure the file is created with the right mode.

I am using the original kernel, but my partition I want to share is in ext3, on an external HDD. I tried specifying setgid bit to the directory, like chmod g+s <group> but it does not work (maybe a umask problem ?). Creating a file with a user make this file not being writable for others...

I mounted the partition in fstab like this : /dev/sda4 /home defaults 0 0Making a cron job to set permissions periodically is _ugly_ solution ;-)

I only brought this up because "man mount" suggested that your (latest) difficulty might be ext3 not supporting umask! I don't have any new suggestions at the moment, other than those above.

Traditionally a common solution for this kind of issue (eg for RCS and CVS repositories accessed through the filesystem) has indeed been as suggested before in theis thread to put everyone concerned into a common group, give the target directory that group, and make it setgid. Fairly reliable and no ACLs needed (I've been using that tecnique for getting on for 15 years on *nix).

Since ext3 is a standard Linux file system you can't specify umask as an option for it. The option is only there for things such as FAT, which don't have a permission mask, UDF, where you might want to change things - etc.